My remembrance was this was an indication of a burned out turn signal, but this is not the case. My right turn signal blinks normally, but the left is much faster. All turn lights seem to be working. :-?
Look again. The Flasher relay is common to both sides of the car. When you move the turn signal stalk one way or the other, you're switching the turn signal lamps from one side of the car (or the other) through the exact same Flasher.
The Flasher can't tell which side of the car it's flashing. If it flashes faster on one side than the other, it's because the electrical load is different on one side than the other. There is no other possible cause for a different left/right blink rate.
There are certainly other things that can cause the electrical load to be different side-to-side, but most of them would either blow a fuse or make smoke. The most probable by a long-long margin is a bulb. You may have missed it. Check again, in the dark, before you waste money on a Dealer service call!
Tip: Use the Hazard flasher instead of the turn signal. The Hazard flasher flashes all the same lamps used for turn signals. But it flashes both the left and right sides at the same time. So with the Hazard flasher going you can walk around the car and compare left/right at the same time. It makes it a little easier to spot differences.